Work on leishmaniasis again dominated most of the effort on this project. An initiative on locating new cases of diffuse cutaneous leishmaniasis (DCL) in Mexico was successful. Six cases of advanced DCL were found in at least 3 different geographic areas of Mexico, where this variety of leishmaniasis has been reported in the past but not emphasized recently. Some of the DCL isolates have been typed as members of the L. mexicana complex. Eight additional new cases of cutaneous leishmaniasis and one new case of mucocutaneous disease, from diverse geographic areas, were diagnosed, evaluated immunologically, and most were treated at NIH. We still have not been able to identify more precisely the immuno-suppressive population of lymphocytes in DCL patients. Experiments with frozen lymphocytes from DCL patients were found to sometimes yield results at variance with those obtained with fresh cells. The collaborative study with WRAIR on the efficacy of a recombinant sporozoite vaccine against P. falciparum in human volunteers was completed. One of six volunteers immunized with 4 doses of the experimental vaccine was protected when challenged with infected mosquitoes three weeks after the last dose of vaccine. Although the vaccine was protective in one individual, the lack of booster response to multiple doses, and re- evaluation of how anti-sporozoite immunity is produced indicate that more basic studies of this type of vaccine for humans are needed.